President Barack Obama and first lady Michelle Obama walk to greet supporters on the tarmac after landing aboard Air Force One at Austin-Bergstrom International Airport in Austin, Texas, Thursday, April 10,,2014. (AP Photo/ Tamir Kalifa)

AUSTIN, Texas (AP) — Reflecting on the unique power of the office he holds, President Barack Obama on Thursday honored Lyndon B. Johnson as leader who seized the presidency’s opportunity to shape the “currents of history” and fulfill America’s founding promises of equality.

“I have lived out the promise of LBJ’s efforts,” Obama said, marking the 50th anniversary of the Civil Rights Act, landmark legislation signed by Johnson that helped clear the way for Obama to become the nation’s first black president.

Obama’s 30-minute remarks at the Johnson presidential library came at the end of a three-day summit commemorating the law that ended racial discrimination in public places. The anniversary has led to a renaissance of sorts for Johnson’s domestic agenda — which also included creation of Medicare, Medicaid and the Voting Rights Act — and renewed appreciation for the 36th president’s mastery of congressional dealmaking.

Obama, who has faced criticism for not replicating Johnson’s tactics with lawmakers, praised his predecessor’s ability to cajole and to strong-arm the civil rights law through Congress over objections from lawmakers in his own party.

“No one knew politics, and no one loved legislating, more than President Johnson,” Obama said. “He was charming when he needed to be, ruthless when required.”

The president also offered rare personal insight into his views on the office he holds, casting it as a humbling perch.

“You’re reminded daily that in this great democracy, you are but a relay swimmer in the currents of history, bound by decisions of those who came before, reliant on the efforts of those who will follow, to fully vindicate your vision,” he said.

For Obama, who was criticized by some African-Americans in his first term for doing too little to help minorities, the commemoration of the Civil Rights Act dovetails with a focus on inequality and economic opportunity that has become an early hallmark of his second term with modest success. Democrats have seized on the broader theme as their battle cry for the election year, and Obama offered his own reminder Thursday that more work must still be done to even the playing field for all Americans.

“The story of America is a story of progress, however slow, however incomplete,” Obama said.

Obama was introduced at Thursday’s event by Rep. John Lewis, D-Ga., who withstood violence and arrest during the civil rights marches through Alabama in the mid-1960s. Lewis said Obama’s election marked a moment when the nation believed it “may have finally realized the vision President Johnson had for all of us — to live the idea of freedom and eliminate the injustice from our beloved country.”